compositions



' I06. COMPOSITIONS,

COATING OR PLASTIC.

UNITED STATES Cross Reference M am; M2,089,752

PATENT OFFICE .PRESSUREPROOF INSULATING -BODIES ES- "PECIALLY FOB ELECTROLYTIC CELLS No Drawing.

-tto Lang, Munich, Germany Original application October 6,

.1932, Serial No. 636,615. god and this application March 11, 1935, me 0. 10,589. In Germany October 10, 1931 4 Claims. (01. 2047B 7'? This invention relates to pressure-proof insulating bodies especially for electrolytic cells.

This application is a division of my copending application Serial No. 636,615, filed October 6,

6 1932, relating to the method of manufacturing such bodies.

The discovery of an insulating constructionmaterial suitable for electrolyzers, especially in connection with the decomposition of water under low or high pressure, has given rise to comparatively great difliculties owing to the great and extensive requirements demanded from such construction-material for these purposes. Insulating materials such as glass, fibre and vulcanite, hitherto employed, can at once be eliminated as not possessing any permanent resisting power to the concentrated electrolytes with their subsequently arising active gases used in these electrolyzers. The use of such non-permanent materials not only leads to the destruction of vital construction elements but also, by the resulting reaction products, the electrolyte will be made impure, thereby having a detrimental effect on the efliciency of the apparatus.

In the category varnis various materials have been discovere aving the power of resistance and constancy which have in every respect proved ei'ficient in withstanding concentrated electrolytes and their'active gases.

30 Foremost in consideration are cellulose-ethercompositions, such as benzyland eEEy'l-beQQ fiie,

co g e as ew years.

It has also proved expedient to mix such varnishes with inorganic fllling giater ial such as as- 35 bestos, powderedasbsto's, powdered slate etBf" "Dh the other hand, these maten' s prove noticeably defective, particularly under high temperature and high pressure, for they have the tendency, under high temperature, of growing 40 soft.

In utilizing these materials, especially for electrolytic cells or containers, as a result of the softening under high temperature, there arises the risk of a deformation under the pressure- 45 load. This deformation is, in the case of construction parts which have channels or must maintain a certain distance from each other, particularly detrimental because, owing to the yielding of the material in the direction of the 50 pressure, e. g., in the case of fllter-press-electrolyzers by movement toward the securing spindles, the distances between the electrodes may be decreased to such an extent as to interfere with the regular passing of the gas-electrolyte-mixture.

55 The yielding of the'material results in its bulging, which will disadvantageously increase the diameter of the cell-body and, what is even of greater danger, will decrease the cross-section of the channels hollowed in the frames, even nanrowing themto such an extent as to make im possible an unimpeded passing oil of the gaselectrolyte-mixture so that the gas will thus accumulate in the cell-spaces, thus resulting in the destruction of the cells.

The problem set by the inventor consists in discovering a medium for overcoming the softening of such materials under high temperature. This is to be effected by admixing t ififgning ggents with the construction materials or their com ponent partswhile still in a plastic state, such stiffening agents possessing the peculiarity of not losing their stillness even under a rising temperature.

Consequently; the method for manufacturing pressure-proof insulating bodies especially for electrolytic cells, of materials or their component parts softening under heat, consists in adding settin or sti fiening substances to the construcll'fl materi lfiqtsf'prasuefiate. This quality of allowing the material to set, and the subsequent consolidation of the admixed sti-ilening substance, result in achieving the desired effeet, for such setting substances, e. g., cement, etc., possess the peculiarity of not afterwhfdldsling their consolidation effected by the setting process, not even under considerably increased temperaturedin; addition, the setting process leads furthermore to the valuable complementary phenomenon that each setting substance expands by the chemical processes taking place, thus allowing the moulds to be well filled out during the moulding process, resulting in a perfect form.

The setting stiffening medium forms within the finished constructional part apgr qgs skeleton, the pores of which are uniformly impregnated with the other construction substances. Even under high temperatures, the finished porous skeleton offers a satisfactory resistance to the compressive force acting upon it, and prevents the yielding and bulging of the construction material, whilst the construction material proper, filling the pores of the skeleton, adds to the construction piece itself the necessary properties, namely, insulating effectiveness, density, etc.

Elements, added to the construction material proper o f tli component parts of the construction material, have to be chiefiyconsidered as stiffening agents whereby, in the case of utilizing cellulose-ether compositions, the quantity of Examiner ma e t and 2 to 3 parts of water has proved advantageous.

The varnish solution can, for example be made by dissolving onaiidit benzyl-cellulose in 10 parts benzene or in a benzene 0 1 e mixture 1: 1. In place of benzyl-ce ose e y -ce lulose or some other cellulose varnis use Now, 4 parts of the thus obtained varnish solution are mixed with one part well-loosened as bestos fibre and thoroughly compounded. There upon, one part Roman cemgnt, first mixed with 2 to 3 parts of water, is added to 5 parts of this pulpy mass, an'd'TH whole is thoroughly intermixed. By this means a kneadabl e, doughy mass results which is easily m olild'abll 'l he'rduire'd" weight of this mass is, for example, now placed in a well-moistened wooden mould and left to dry for some time to allow the solution agent to escape. The final stability and shape is obtained by gradual firm pressing and drying of the mass in steel moulds. Care has to be taken that the cement has not entirely been allowed to set prior to the final pressing process as, otherwise, the inner structure is liable to be demolished.

In place of an immediate shaping of the form, it is of advantage to spread out the plastic doughy mass in thin layers and thus allowing the solution agent or solvent to evaporate. Prior to the layer being entirely dried out, it is completely torn apart into small pieces by a shredding machine and placed in a mmflg fiig Q which can be made of steel. The mass is pressed under high power, resulting in a solid moulded article.

This additional process has the advantage of shortening the working process on account of the easily evaporable solution escaping fairly quickly from the thin mass, whilst it takes longer for it to rise from the interior of the body to the surface and to evaporate therefrom. In the latter case, the solution agent generally carries some cellulose can with it, which causes the disadvantage of the inner layers becoming impoverished in cellulose.

Whilst it is possible for the body to be produced in two stages of pressing according to the second process, 8 to 10 stages of pressing are required with the first process.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. A pressure-proof body for constituting an impermeable portion of an electrolytic cell comprising a rigid skeleton of a heat-resistant fibrous material and a heat-resistant hydraulic cement uniting the fibers to form the skeleton, said skeleton having its pores uniformly filled and closed by a cellulose-ether of the group consisting of benzyl and ethyl cellulose, said body having been formed by intermixing the fibrous material, the cement and the cellulose-ether and then forming the same under heat and pressure prior to the setting of the cement.

2. A pressure-proof body for constituting an impermeable portion of an electrolytic cell comprising a rigid skeleton of a heat-resistant fibrous material and a heat-resistant hydraulic cement uniting the fibers to form the skeleton, said skeleton having its pores uniformly filled and closed by benzyl cellulose, said body having been formed by intermixing the fibrous material, the cement and the benzyl cellulose and then forming the same under heat and pressure prior to the setting of the cement.

3. A pressure-proof body for constituting an impermeable portion of an electrolytic cell comprising a rigid skeleton of a heat-resistant fibrous material and a heat-resistant hydraulic cement uniting the fibers to form the skeleton, said skeleton having its pores uniformly filled and closed by ethyl cellulose, said body having been formed by intermixing the fibrous material, the cement and the ethyl cellulose and then forming the same under heat and pressure prior to the setting of the cement.

4. A pressure-proof body for constituting an impermeable portion of an electrolytic cell comprising a rigid porous skeleton of particles of a heat-resistant non-conductive mineral filling material and a heat-resistant water-hardened cement including water of combination uniting the particles of said material to form the skeleton,

said skeleton having its pores uniformly filled and closed by a cellulose-ether of the group consisting of benzyl and ethyl cellulose, said body having been formed by intermixing the inorganic material, the cement and the cellulose-ether and then forming the same under heat and pressure prior to the setting of the cement.

O'I'I'O LANG. 

